Field of the Invention
The present invention relates to shift registers, and in particular to shift registers in an in-cell touch panel.
Description of the Related Art
Shift registers are widely applied in data driving circuits and gate driving circuits, for controlling the sequences of each data line sampling data signal and generating a scan signal for each gate line. In the data driving circuit, a shift register is used for outputting a select signal to each data line, so that the image data can be written into each data line sequentially. On the other hand, in the gate driving circuit, a shift register is used for generating a scan signal to each gate line, so that the image signals provided to each data line can be written into each pixel.
Usually a gate driving circuit of a panel without touch function includes a plurality of shift registers. Each shift register receives an output signal from a pre-stage shift register and the output signal is as an activating signal of the shift register. As for operation of a gate driving circuit of the touch panel, because it has to detect whether the touch panel is touched, the conventional gate driving circuit and the driving method cannot be applied to the touch panel directly.
FIG. 1 is a diagram of a conventional gate driving circuit. The gate driving circuit in FIG. 1 includes a plurality of shift registers SRC1, SRC2 to SRCN. Except for the shift register in the first stage receiving the activating signal STV to be enabled, other shift registers are enabled when receiving an output signal from a pre-stage shift register, and the shift register is disabled (i.e. turned off) when receiving an output signal of the next-stage shift register. However, regarding the driving mechanism of the touch panel, some period of time must be reserved for touch sensing on the touch panel. In a touch sensing period, the gate driving circuit must stop working temporarily. As a result, the shift register could be unable to receive the output signal of the pre-stage shift register correctly to be turned on, or could be unable to receive the output signal of the next-stage shift register correctly to be turned off.